Response time is how quickly a display pixel can shift from one colour to another, typically measured in milliseconds (ms). A monitor with a 1ms response time changes colour faster than one with 5ms. This matters most when you're watching movement on screen, especially in games, sports, or action films.
When response time is slow, you'll notice ghosting or motion blur. A player character moves across the screen, and you see a faint trail behind them. Fast response times eliminate this trailing effect, keeping edges sharp during rapid motion.
Different display types have different typical response times. LCD panels commonly achieve 1ms to 5ms. IPS panels, prized for colour accuracy, traditionally had slower response times but modern versions reach 4ms or better. VA panels and TN panels often hit 1ms to 3ms. OLED displays respond almost instantly, typically under 1ms, since they emit their own light.
Real-world example: you're playing a fast-paced shooter. A monitor with poor response time leaves a ghostly outline trailing your crosshair. With a quick-responding monitor, your aim looks crisp and responsive.
When buying, check the manufacturer's quoted response time. Be sceptical of marketing claims like "0.5ms fastest mode", these sometimes use edge-to-edge measurements that don't reflect typical use. Look for grey-to-grey (g-to-g) or black-to-white measurements, which are more standardised. If you mainly browse the web or edit documents, response time under 5ms is fine. Gamers and anyone watching fast motion should prioritise 4ms or faster.